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 A308412 Indices of Gaussian primes on a square spiral. 1
 3, 5, 7, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 52, 54, 60, 62, 68, 70, 76, 78, 82, 84, 88, 90, 92, 94, 98, 100, 102, 104, 108, 110, 112, 114, 118, 120, 122, 126, 128, 132, 134, 138, 140, 144, 146, 150, 152, 156, 158 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS These are the numbers k > 0 such that A174344(k) + i*A274923(k) is a Gaussian prime (where i denotes the imaginary unit). For symmetry reasons, we obtain the same sequence when considering a clockwise or a counterclockwise square spiral, or when initially moving towards any unit direction. All terms except the first four are even. LINKS Rémy Sigrist, PARI program for A308412 Eric Weisstein's World of Mathematics, Gaussian Prime EXAMPLE The first terms displayed on the center of a counterclockwise square spiral are:   y\x|    -5   -4   -3   -2   -1    0   +1   +2   +3   +4   +5   ---+--------------------------------------------------------    +5|     *--100----*---98----*----*----*---94----*---92----*      |     |                                                 |    +4|   102    *----*----*---62----*---60----*----*----*   90      |     |    |                                       |    |    +3|     *    *    *---36----*---34----*---32----*    *    *      |     |    |    |                             |    |    |    +2|   104    *   38    *---16----*---14----*   30    *   88      |     |    |    |    |                   |    |    |    |    +1|     *   68    *   18    5----*----3   12    *   54    *      |     |    |    |    |    |         |    |    |    |    |     0|     *    *   40    *    *    *----*    *   28    *    *      |     |    |    |    |    |              |    |    |    |    -1|     *   70    *   20    7----*----9---10    *   52    *      |     |    |    |    |                        |    |    |    -2|   108    *   42    *---22----*---24----*---26    *   84      |     |    |    |                                  |    |    -3|     *    *    *---44----*---46----*---48----*----*    *      |     |    |                                            |     4|   110    *----*----*---76----*---78----*----*----*---82      |     |     5|     *--112----*--114----*----*----*--118----*--120----* PROG (PARI) See Links section. CROSSREFS Cf. A174344, A274923. Sequence in context: A214315 A249098 A287774 * A327254 A054684 A294601 Adjacent sequences:  A308409 A308410 A308411 * A308413 A308414 A308415 KEYWORD nonn AUTHOR Rémy Sigrist, Jun 01 2019 STATUS approved

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Last modified October 22 01:46 EDT 2020. Contains 337948 sequences. (Running on oeis4.)